Get a Soil Test for Satsuma

Q: I planted a healthy Satsuma orange tree in my front yard in full sun about five years ago. I have fed it regularly and kept it watered. It is very healthy and puts on good new growth every year, but every spring after a fruit set of up to several hundred oranges, every single one of them turns yellow and drops off within about three weeks. I have never sprayed it with any pesticide. I can’t find anything on the Internet to tell me what’s wrong. I have friends in the Tallahassee area with enormous crops on their trees every year. What’s the problem with my poor tree?

A: Some fruit drop on citrus is normal, because the tree produces more fruit than it can sustain to maturity and naturally thins out some of it. Excessive fruit drop, however, is a sign the tree is under stress and can be caused by several things; often, it’s a combination of more than one factor.

First, get a soil test done. You can get the kit and directions at your county Extension Service office. The instructions will tell you to collect soil from several areas of the planting bed, so take samples from all around the tree, as far out as the canopy extends. Ask for the full soil analysis, not just the pH, or soil acidity, test. Potassium deficiency can cause of fruit drop, especially if your tree is trying to produce a heavy crop, and that is one ailment that is easy to diagnose and remedy. It will also tell you whether you need additional micronutrients.

The soil test will also tell you whether you’re over-fertilizing your tree. Hold off on applying any more fertilizer until you know what elements are present in your soil, and at what levels.

Uniform and adequate watering is critical in preventing fruit drop. You said you’ve kept it watered; is there a possibility you’ve overwatered it? If the area doesn’t have good drainage, the roots will get soggy and that will cause fruit drop.

It could be that your tree is trying to produce too much fruit. If your tree is only five years old, it probably can’t sustain several hundred fruit to maturity. Try removing at least half, maybe three-fourths, of the fruit as soon as it sets, so the tree can put its energy into developing the remaining fruit to maturity. As it gets bigger, it can handle a larger crop.

Betony note: Steve Christman from Floridata.com wrote to say it’s the corms, not the leaves, of Florida betony that are edible, but he added that they’re not particularly flavorful. He described them as "virtually tasteless. "